The following description will refer explicitly to the production and packaging of the above articles, without losing its general character.
There are manufacturing or in-bagging machines, which fabricate welded tubular wrappings or bags of the type known as flow-pack, containing granular substances therein.
More in detail, the in-bagging machines produce bags beginning from a continuous sheet, of e.g. heat-weldable paper, which is preliminarily cut, so as to define a plurality of strips, vertically parallel.
Afterwards, each of the strips is brought to a tubular configuration by suitable folding means and then welded longitudinally along the edges.
In step relation with the longitudinal welding, the bottom of each vertical strip is also welded and afterwards, a measured quantity of the predetermined granular or powder substance is filled into the flow-pack.
When the filling is completed, each strip is welded again at top and cut near the median line of the welded portion, so as to detach it from the continuous sheet and to define the bottom of a subsequent tubular structure.
The so obtained sealed tubular bags, usually arranged one beside another in longitudinal vertical configuration, are withdrawn at the outlet portion of the in-bagging machine by suitable withdrawing and transferring means (for example by conventional suction means known as “pick and place”), and later fed, arranged longitudinally horizontally, to corresponding hoppers of an outlet station of the bag filling machine.
After the bags have been placed in the hoppers, the bottom of the hoppers are opened, so that the tubular bags are released to fall into corresponding boxes of a box conveyor, which constitutes an inlet portion of a packaging machine, aimed at packaging groups of bags into cases.
In order to ensure best and efficient transferring of the sealed tubular bags from the bagging machine to the packaging machine, the distance between the axes of two consecutive hoppers, or step, must be substantially equal to the corresponding step of the box-compartments of the packaging machine conveyor.
In this way, a correct filling of the conveyor box-compartments with a predetermined number of tubular bags is ensured.
Therefore, according to the above described known method, when the size of the tubular bags is changed, that is when one wants to produce tubular bags of different transverse dimensions, the step between the above hoppers, i.e. the distance between the hoppers, must be changed, and consequently, the step or distance between different box-compartments of the packaging machine conveyor must be adjusted and changed.
As it is easily understood, such changes result in difficult and complicated adjustment work, which causes long downtimes.